A method for the preparation of such products is described, in particular, in US2003/0181443.
However, the first step of this method involves 3-chloro-3-methylbut-1-yne the supply of which may be uncertain. In addition, the purity of the commercial product is variable and may have an impact on the remainder of the reaction chain, particularly in terms of yield. Moreover, the purification steps for this first step appear to be difficult to transpose to a large scale, while the product of this first step tends making the purification steps all the more difficult.
The second step of this method uses carbon oxysulfide (COS) which is a toxic product and the supply of which is uncertain depending on the country.
It is therefore necessary to provide a method to solve the disadvantages of the prior art.